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Aqueous Zn/MnO2 batteries with their environmental sustainability and competitive cost, are becoming a promising, safe alternative for grid-scale electrochemical energy storage.

Developing advanced electrode architectures through modifying active materials, conductive fillers, binders, and electrolytes as well as processing methods has drawn significant research interest. Due to the insufficient electrical conductivity of many active materials, adding conductive carbon fillers to composite electrodes provides the necessary electrical conductivity. The dimensionality effect among different conductive fillers has a significant impact on electrochemistry, which can be associated with morphological and chemical heterogeneities of electrodes. Here, synchrotron X-ray mosaic nanotomography and X-ray spectroscopy nanoimaging provided direct three-dimensional (3D) visualization and quantification capabilities to investigate the dimensionality effects of Super P (SP) and single-walled carbon nanotube (SWCNT) fillers on the capacity retention of LiNi1/3Mn1/3Co1/3O2 (NMC111). The results indicate that NMC/SWCNT electrodes, with a wrapping effect from the SWCNTs, exhibited more homogeneous particle size distributions, morphological changes, and chemical states than NMC/SP electrodes, without the wrapping effect. This work developed a framework of 3D quantification methods to study the capacity fading behavior associated with morphological and chemical heterogeneities and paved the way toward designing electrodes for high rate energy storage applications.

Thin-film solid-state interfacial dealloying (thin-film SSID) is an emerging technique to design nanoarchitecture thin films. The resulting controllable 3D bicontinuous nanostructure is promising for a range of applications including catalysis, sensing, and energy storage. Using a multiscale microscopy approach, we combine X-ray and electron nano-tomography to demonstrate that besides dense bicontinuous nanocomposites, thin-film SSID can create a very fine (5–15 nm) nanoporous structure. Not only is such a fine feature among one of the finest fabrications by metal-agent dealloying, but a multilayer thin-film design enables creating nanoporous films on a wider range of substrates for functional applications. Through multimodal synchrotron diffraction and spectroscopy analysis with which the materials’ chemical and structural evolution in this novel approach is characterized in details, we further deduce that the contribution of change in entropy should be considered to explain the phase evolution in metal-agent dealloying, in addition to the commonly used enthalpy term in prior studies. The discussion is an important step leading towards better explaining the underlying design principles for controllable 3D nanoarchitecture, as well as exploring a wider range of elemental and substrate selections for new applications.

A novel facile, fast, and efficient microwave-assisted method was developed to synthesize a number of diverse nanostructured motifs (ranging from nanorods to nanoflowers) of VS4 along with its asso...

Multiscale porous metals with multiscale porosity from nanometer to micrometer have a high specific surface area and high effective diffusivity for ion transport, thereby enhancing functionalities ...

This report summarizes the outcome of a workshop, “Multimodal Synchrotron Approach—Research Needs and Scientific Vision,” held during the National Synchrotron Light Source–II (NSLS-II)/Center for F...

Titanium disulfide (TiS2) with high electric conductivity, fast rate capability, and good cycling performance is a promising candidate for electrode material in sodium (Na)-ion batteries. Despite the well-studied electrochemical behaviors of TiS2 in Li-ion batteries, the detailed reaction mechanism of TiS2 in Na-ion batteries is not yet fully understood due to a more complex multi-phase conversion process. In this work, reactions of TiS2 in Na-ion batteries are investigated via a multi-modal synchrotron approach: operando X-ray Absorption Spectroscopy (XAS) – including X-ray Absorption Near-Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) – and ex situ X-ray Powder Diffraction (XPD), coupled with computational modeling. Operando XANES spectra indicate that the redox reactions occur in both Ti and S during the electrochemically driven phase transformation. Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) analysis of XAS suggests that different numbers of components are involved in the lithiation and sodiation of TiS2, with the sodiation including at least one intermediate phase in addition to the starting material and the final sodiation product. Ex situ XPD and Rietveld refinement further determined and quantified the unknown phases, showing that three phases, TiS2, Na0.55TiS2, and NaTiS2, participate in the sodiation of TiS2. Operando EXAFS results show the changes in the Ti–Ti coordination number and interatomic distance. This explains the coulombic efficiency decay due to the incomplete recovery of the coordination number of Ti after cycling. Overall, this work reveals the reaction mechanism occurring in Na–TiS2 batteries with a greater quantitative understanding of the structural evolution. By combining the multi-modal synchrotron approach and computational work, this study provides a framework for studying a broader range of electrochemically driven phase-transformation systems towards advanced energy storage and conversion applications.

Designing materials with multiscale, hierarchical structure is critical to drive the advancement of new technology. Specifically, porous metals with multiscale porosity from nanometer to micrometer sizes would lead to enhanced physical and chemical properties-the micron-sized pores can increase the effective diffusivity of ion transport within the porous media, and the nano-sized pores provide high specific surface area, enabling functionalities that are unique to nanoporous metals. A new ternary precursor alloy selection concept utilizing the different mixing enthalpies is demonstrated in this work for the design of multiscale, bimodal porous copper from a simple, one-step dealloying of Cu-Fe-Al ternary alloy. The nanoporosity in the bimodal porous structure is formed from dealloying of the Cu-rich phase, whereas the microporosity is controlled by dissolving the Fe-rich phase, determined by both the initial Fe particle size and sintering profile. In addition to advancing the materials design method, the multiscale pore formation during dealloying was directly visualized and quantified via an interrupted in situ synchrotron X-ray nano-tomography. The 3D morphological analysis on tortuosity showed that the presence of the microporosity can compensate the increase of the diffusion path length due to nanoporosity, which facilitates diffusion within the porous structure. Overall the focus of the work is to introduce a new strategy to design multiscale porous metals with enhanced transport properties, and sheds light on the fundamental mechanisms on the 3D morphological evolution of the system using advanced synchrotron X-ray nano-tomography for future materials development and applications.

Soils regulate the environmental impacts of trace elements, but direct measurements of reaction mechanisms in these complex, multi-component systems can be challenging. The objective of this work was to develop approaches for assessing effects of co-localized geochemical matrix elements on the accumulation and chemical speciation of arsenate applied to a soil matrix. Synchrotron X-ray fluorescence microprobe (µ-XRF) images collected across 100 µm × 100 µm and 10 µm × 10 µm regions of a naturally weathered soil sand-grain coating before and after treatment with As(V) solution showed strong positive partial correlations (r′ = 0.77 and 0.64, respectively) between accumulated As and soil Fe, with weaker partial correlations (r′ > 0.1) between As and Ca, and As and Zn in the larger image. Spatial and non-spatial regression models revealed a dominant contribution of Fe and minor contributions of Ca and Ti in predicting accumulated As, depending on the size of the sample area analyzed. Time-of-flight secondary ion mass spectrometry analysis of an area of the sand grain showed a significant correlation (r = 0.51) between Fe and Al, so effects of Fe versus Al (hydr)oxides on accumulated As could not be separated. Fitting results from 25 As K-edge microscale X-ray absorption near-edge structure (µ-XANES) spectra collected across a separate 10 µm × 10 µm region showed ∼60% variation in proportions of Fe(III) and Al(III)-bound As(V) standards, and fits to µ-XANES spectra collected across the 100 µm × 100 µm region were more variable. Consistent with insights from studies on model systems, the results obtained here indicate a dominance of Fe and possibly Al (hydr)oxides in controlling As(V) accumulation within microsites of the soil matrix analyzed, but the analyses inferred minor augmentation from co-localized Ti, Ca and possibly Zn.

Aqueous Zn-ion batteries has attracted great attention in recent years, as a promising candidate for grid energy storage applications. An aqueous system offers intrinsic safety, high ionic conductivity contributing improved power capability and raw materials that are more earth abundant and environment friendly. Numerous promising reports haven been focusing on the Zn/MnO2 system owing to its low cost, moderate discharge potentials and with improved reversibility in the mild aqueous electrolyte. However, many questions remain unanswered regarding its reaction mechanism. The different reaction mechanisms including Zn+2 insertion, H+ insertion, chemical conversion reaction including the combined intercalation and conversion reaction mechanism, and the dissolution-deposition of the manganese oxide. In this work, we aim to unravel the reaction mechanism by a systematic multimodal synchrotron characterization. This work discusses the galvano-static charge-discharge process of aqueous Zn-MnO2 batteries using operando measurements, which provides us with a direct insight into the phenomenon and can be directly correlated to the battery's electrochemical response. The multimodal techniques include operando X-ray diffraction to study the structural phase change of the cathode active material, operando X-ray absorption spectroscopy to probe the local structure changes and transmission X-ray microscopy studies to observe the key morphological events. Overall, this multimodal approach gives us an insight into the reaction mechanism enabling us to better design Zn-MnO2 batteries for practical applications.

Lithium-ion batteries are widely used today in powering devices from portable electronics to electric vehicles. Despite their great success, this battery chemistry relies on organic solvent-based liquid electrolytes which are highly flammable, leading to major safety concerns. In contrast, solid-state batteries, which are based on solid-state electrolytes, are regarded to have much better safety characteristics and potentially higher energy density than the conventional lithium-ion batteries. Solid-state electrolytes usually include ceramics, polymers, gels, and composites. Among them, polymer materials have attracted considerable attention due to their great interfacial contact, flexibility, and easy fabrication. In particular, polyvinylidene fluoride (PVDF) polymer electrolyte is a promising candidate as it can potentially provide a high voltage window and enable high energy density solid-state batteries. However, the current PVDF-based polymer electrolyte is still not compatible with high voltage cathodes, such as layered lithium transition metal oxides and the interaction between the salt and PVDF polymer has not been fully elucidated. We have systematically studied the PVDF-based electrolytes with different salts and salt combinations, including lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(pentafluoroethanesulfonyl)imide (LiBETI). The optimized electrolyte delivers excellent performance for solid-state Li||LiFePO4 cells, achieving a specific capacity of over 150 mAh/g and lasting more than 50 cycles with over 99% capacity retention. Similar tests have also been applied to lithium nickel manganese cobalt oxides (NMC), and the preliminary results show promising cycling stability and capacity retention. In addition to electrochemical study, we employed a range of synchrotron-based X-ray techniques, including diffraction, pair distribution function analysis, and absorption spectroscopy, to investigate the interactions between the polymer and lithium salt in the polymer electrolytes. This knowledge will provide valuable information for designing new polymer electrolyte systems. Acknowledgments: The work at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. Department of Energy through the Advanced Battery Materials Research (BMR) Program under contract DE-SC0012704. This research used beamline 23-ID-2 and 28-ID-2 of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.

As batteries revolutionize all technological areas – from miniaturized electronic devices to electric vehicles and to large-scale energy storage, understanding the complex morphological, chemical and structural evolution and their interplays has been at the forefront of the research. Synchrotron X-ray characterization techniques provide insights into the electrochemical reactions and multiscale, multiphysics environments to address the fundamental mechanisms in these systems. The presentation will highlight the application of synchrotron X-ray analysis in two Li-ion battery systems, including both aqueous and non-aqueous systems. X-ray nano-tomography via transmission X-ray microscopy and spectroscopic imaging, complemented by other diffraction, spectroscopy and microscopy techniques, will be discussed. We will present how synchrotron X-ray nano-tomography and quantitative 3D morphological analysis were instrumental in revealing the dimensionality effect of conductive carbon fillers in LiNi 1/3Mn1/3Co1/3O2 (NMC111) cathode [1]. Additionally, we will discuss how a multimodal characterization approach offered insights when probing kinetics of water-in-salt aqueous batteries with thick, porous LiV3O8-LiMn2O4 electrodes [2, 3]. Through the morphological and chemical analyses, the work aims to facilitate the design of future advanced energy storage materials, as well as provide a novel characterization framework for studying a wider range of electrochemical systems. References: [1] "Dimensionality effect of conductive carbon fillers in LiNi 1/3Mn 1/3Co 1/3O 2 cathode", Cheng-Hung Lin, Zhengyu Ju, Xiaoyin Zheng, Xiao Zhang, Nicole Zmich, Xiaoyang Liu, Kenneth J. Takeuchi, Amy C.Marschilok, Esther S.Takeuchi, Mingyuan Ge, Guihua Yu, Yu-chen Karen Chen-Wiegart, Carbon (2021), DOI: https://doi.org/10.1016/j.carbon.2021.11.014 [2] "Probing Kinetics of Water-in-Salt Aqueous Batteries with Thick Porous Electrodes", Cheng-Hung Lin, Lei Wang, Steven T. King, Jianming Bai, Lisa M. Housel, Alison H. McCarthy, Mallory N. Vila, Hengwei Zhu, Chonghang Zhao, Lijie Zou, Sanjit Ghose, Xianghui Xiao, Wah-Keat Lee, Kenneth J. Takeuchi, Amy C. Marschilok, Esther S. Takeuchi, Mingyuan Ge, and Yu-chen Karen Chen-Wiegart, ACS Central Science (2021), DOI: 10.1021/acscentsci.1c00878 [3] "Systems-Level Investigation of Aqueous Batteries for Understanding the Benefit of Water-In-Salt Electrolyte by Synchrotron Nano-Imaging", Cheng-Hung Lin, Ke Sun, Mingyuan Ge, Lisa Housel, Alison McCarthy, Mallory Vila, Chonghang Zhao, Xianghui Xiao, Wah-Keat Lee, Kenneth J. Takeuchi, Esther S. Takeuchi, Amy C. Marschilok, Yu-chen Karen Chen-Wiegart, Science Advances (2020), DOI: 10.1126/sciadv.aay7129

The use of molten salts for large-scale solar concentrated power plants and molten salt reactors has been driving the research to better understand how metals and alloys interact with the molten salt. As the metals may undergo morphological, chemical, and structural change in molten salt environments, it is critical to understand the fundamental mechanisms in these changes. In this work, we will present how we utilized synchrotron X-ray nano-tomography to better understand the 3D morphological evolution of Ni, Cr, and their alloys in molten salt. The effects of temperature and additives in the salt on the morphological evolution will be discussed. At the higher temperature, a characteristic bicontinuous structure can form from molten salt dealloying a binary alloy. [1] This contrasts to the intergranular corrosion found in the same system reacted at a lower temperature. [2] Different additives in the salt were also found to alter the morphological changes of the alloys and can create planar corrosion, percolation dealloying, or redeposition. To complement the morphological studies by X-ray nano-tomography, a suite of X-ray and electron microscopy analyses were also carried out to better understand the chemical and structural (both short-and long-range ordering) evolution. Taking it as a multimodal approach, we will discuss how we couple the analysis from synchrotron operando X-ray absorption spectroscopy, diffraction, and imaging, as well as the multiscale imaging studies from both X-ray and electron microscopy. This work was supported as part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center (EFRC), funded by the U.S. Department of Energy, Office of Science. References: [1] "Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography" Xiaoyang Liu, Arthur Ronne*, Lin-Chieh Yu, Yang Liu, Mingyuan Ge, Cheng-Hung Lin, Bobby Layne, Phillip Halstenberg, Dmitry S. Maltsev, Alexander S. Ivanov, Stephen Antonelli, Sheng Dai, Wah-Keat Lee, Shannon M. Mahurin, Anatoly I. Frenkel, James F. Wishart, Xianghui Xiao & Yu-chen Karen Chen-Wiegart* Nature Communications (2021), DOI: 10.1038/s41467-021-23598-8 [2] "Visualizing time-dependent microstructural and chemical evolution during molten salt corrosion of Ni-20Cr model alloy using correlative quasi in situ TEM and in situ synchrotron X-ray nano-tomography" Kaustubh Bawane, Xiaoyang Liu, Ruchi Gakhar, Michael Woods, Mingyuan Ge, Xianghui Xiao, Wah-Keat Lee, Philip Halstenberg, Sheng Dai, Shannon Mahurin, Simon M. Pimblott, James F. Wishart, Yu-chen Karen Chen-Wiegart*, Lingfeng He* Corrosion Science (2021), DOI: 10.1016/j.corsci.2021.109962

Sodium-ion batteries promise low-cost energy storage for the grid and electric vehicles, building upon the established “rocking-chair” Li-ion design, while benefitting from the natural abundance of sodium and the ability to utilize iron or copper redox reactions to further reduce the material cost. Nonetheless, Na-ion adoption has been hindered due to low energy density and large structural changes leading to poor long-term cyclability. It has been recently shown that additional reversible capacity can be obtained through oxygen redox with low voltage hysteresis in selected Na-ion layered oxide cathodes. However, the mechanisms and the intermediate species that enable this reversible oxygen redox are highly debated and not fully understood. Here we focus on several P3-structured sodium-deficient NaxY1/3Mn2/3O2 cathodes, where Y can be Cu or derivatives with partial lithium substitution, to elucidate how lithium substitution influences both the redox mechanism and the structural evolution during electrochemical cycling. Our results show a small amount (~7%) of lithium substitution can change the reaction pathway from a two-phase reaction to a solid solution mechanism, increasing stability and capacity retention. A multimodal characterization approach combining synchrotron-based X-ray spectroscopy, microscopy, and scattering techniques along with nuclear magnetic resonance spectroscopy, provides insights into the redox mechanisms, chemical species distribution, structural evolution, and phase transitions during electrochemical cycling. Acknowledgment: The work at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. Department of Energy through the Advanced Battery Materials Research (BMR) Program under contract DE-SC0012704. This research used resources of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.

Thin-film solid-state interfacial dealloying (thin-film SSID) is an emerging technique to design nanoarchitecture thin films. The resulting controllable 3D bicontinuous nanostructure is promising for a range of applications including catalysis, sensing, and energy storage. Using a multiscale microscopy approach, we combine X-ray and electron nano-tomography to demonstrate that besides dense bicontinuous nanocomposites, thin-film SSID can create a very fine (5-15 nm) nanoporous structure. Not only is such a fine feature among one of the finest fabrications by metal-agent dealloying, but a multilayer thin-film design enables creating nanoporous films on a wider range of substrates for functional applications. Through multimodal synchrotron diffraction and spectroscopy analysis with which the materials' chemical and structural evolution in this novel approach is characterized in details, we further deduce that the contribution of change in entropy should be considered to explain the phase evolution in metal-agent dealloying, in addition to the commonly used enthalpy term in prior studies. The discussion is an important step leading towards better explaining the underlying design principles for controllable 3D nanoarchitecture, as well as exploring a wider range of elemental and substrate selections for new applications.

Aqueous electrochemical systems suffer from a low energy density due to a small voltage window of water (1.23 V). Using thicker electrodes to increase the energy density and highly concentrated “water-in-salt” (WIS) electrolytes to extend the voltage range can be a promising solution. However, thicker electrodes produce longer diffusion pathways across the electrode. The highly concentrated salts in WIS electrolytes alter the physicochemical properties which determine the transport behaviors of electrolytes. Understanding how these factors interplay to drive complex transport phenomena in WIS batteries with thick electrodes via deterministic analysis on the rate-limiting factors and kinetics is critical to enhance the rate-performance in these batteries. In this work, a multimodal approach—Raman tomography, operando X-ray diffraction refinement, and synchrotron X-ray 3D spectroscopic imaging—was used to investigate the chemical heterogeneity in LiV3O8–LiMn2O4 WIS batteries with thick porous electrodes cycled under different rates. The multimodal results indicate that the ionic diffusion in the electrolyte is the primary rate-limiting factor. This study highlights the importance of fundamentally understanding the electrochemically coupled transport phenomena in determining the rate-limiting factor of thick porous WIS batteries, thus leading to a design strategy for 3D morphology of thick electrodes for high-rate-performance aqueous batteries., Multimodal Raman and synchrotron X-ray analysis reveals that the rate-limiting factor of thick porous LiMn2O4 electrodes in a water-in-salt electrolyte is the ionic diffusion in the liquid phase. The finding furthers the understanding of kinetics in an aqueous system for electrochemical energy storage with highly concentrated electrolytes, guiding the future design of advanced 3D-architecture electrodes.

Three-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography. Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal. In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants., Understanding how pores evolve in metals submerged in molten salts is important for nanofabrication technology and molten salt corrosion in nuclear and solar power plants. Here, the authors present an in situ X-ray 3D imaging to directly visualize and quantify the process.

Chemical conversion coating as an effective corrosion inhibition has wide range of applications in industries and is of great expectation to be environmentally friendly and cost-effective. Zirconiu...

To isolate injection and production zones from overlying formations and aquifers during geothermal operations, cement is placed in the annulus between well casing and the formation. However, wellbore cement eventually undergoes fractures due to chemical and physical stress with the resulting time and cost intensive production shutdowns and repairs. To address this difficult problem, a polymer-cement (composite) with self-healing properties was recently developed by our group. Short-term thermal stability tests demonstrated the potential of this material for its application in geothermal environments. In this work, the authors unveil some of the physical and chemical properties of the cement composite in an attempt to better understand its performance as compared to standard cement in the absence of the polymer. Among the properties studied include material's elemental distribution, mineral composition, internal microstructure, and tensile elasticity. Polymer-cement composites have relatively larger, though not interconnected, levels of void spaces compared to conventional cement. Most of these void spaces are filled with polymer. The composites also seem to have higher levels of uncured cement grains as the polymer seems to act as a retarder in the curing process. The presence of homogeneously-distributed more flexible polymer in the cement brings about 60–70% higher tensile elasticity to the composite material, as confirmed experimentally and by density-functional calculations. The improved tensile elasticity suggests that the composite materials can outperform conventional cement under mechanical stress. In addition, calculations indicate that the bonding interactions between the cement and polymer remain stable over the range of strain studied. The results suggest that this novel polymer-cement formulation could represent an important alternative to conventional cement for application in high-temperature subsurface settings.

Bicontinuous-nanostructured materials with a three-dimensionally (3D) interconnected morphology offer unique properties and potential applications in catalysis, biomedical sensing and energy storage. The new approach of solid-state interfacial dealloying (SSID) opens a route for fabricating bi-continuous metal–metal composites and porous metals at nano-/meso-scales via a self-organizing process driven by minimizing the system's free energy. Integrating SSID and thin film processing fully can open up a wide range of technological opportunities in designing novel functional materials; to-date, no experimental evidence has shown that 3D bi-continuous films can be formed with SSID, owing to the complexity of the kinetic mechanisms in thin film geometry and at nano-scales, despite the simple processing strategy in SSID. Here, we demonstrate that a fully-interconnected 3D bi-continuous structure can be achieved by this new approach, thin-film-SSID, using Fe–Ni film dealloyed by Mg film. The formation of a Fe–MgxNi bi-continuous 3D nano-structure was visualized and characterized via a multi-scale, multi-modal approach, combining electron transmission microscopy with synchrotron X-ray fluorescence nano-tomography and absorption spectroscopy. Phenomena involved with structural formation are discussed. These include surface dewetting, nano-size void formation among metallic ligaments, and interaction with a substrate. This work sheds light on the mechanisms of the SSID process, and sets a path for manufacturing of thin-film materials for future nano-structured metallic materials.

Nanostructured silicon with its high theoretical capacity and ability to accommodate volume expansion has attracted great attention as a promising anode material for Lithium ion (Li-ion) batteries. Liquid metal dealloying method, is a novel method to create nanoporous silicon (np-Si). The assembled Li-ion batteries based on such np-Si anode can be cycled beyond 1500 cycles, in 1000 mA h/g constant capacity cycling mode with consistent performance; however, it suffers from degradation after ~ 460 cycles, while being cycled under 2000 mA h/g. To reveal the failure mechanism and differences in the morphological evolution in different capacity cycling modes in the np-Si anode, we conducted synchrotron X-ray nano-tomography studies. The three dimensional (3D) morphological evolution was visualized and quantified as a function of the number of cycles and cycling capacities. By comparing the 3D morphology under each cycling condition and correlating these 3D morphological changes with cycling-life performance, we elucidate the failure mechanism of the np-Si electrodes resulting from a mesoscopic to macroscopic deformation, involving volume expansion and gradual delamination. In particular, the shorter cycling life in higher-capacity cycling mode stems from particle agglomeration. Overall, while the nanoporous structure can accommodate the volume expansion locally, these mesoscopic and macroscopic deformations ultimately result in heterogeneous stress distribution with faster delamination. The work thus sheds the light on the importance to consider the structural evolution at the mesoscopic and macroscopic scales, while designing nano-structured energy storage materials for enhanced performances, particularly for long cycling-life durability.

Corrosion protection is of great importance, since corrosion on metals and alloys happens in a wide range of applications and causes economic and environmental issues. Among various corrosion protection methods, chemical conversion coatings applied by a simple solution immersion process on different metals as a pretreatment has great advantages. The technique is easy to operate and economic. The resulting conversion coatings then act as an effective barrier to corrosion, as well as improving the adhesion between the metal/alloy substrate and the subsequent organic coating. As conventional chromate and phosphate conversion coating treatment has health and environmental issues, there is a strong motivation to develop novel environmentally friendly chemical conversion coatings with comparable functionality. Specifically, zirconium-based (Zr-based) conversion coatings created by immersing alloy substrates in hexafluorozirconic acid (H2ZrF6) solution is an outstanding candidate because of its lower operational cost and fast deposition, while offering good anti-corrosion and adhesion properties.1 Prior works of Zr-based conversion coatings have been focusing on further improving their anti-corrosion performance by controlling the coating deposition parameters including temperature, time, pH value and incorporating organic (silane, phosphonic acids) or inorganic (copper, cerium) compounds. In this study, a novel organic-inorganic hybrid Zr-based conversion coating with copper (Cu) and polyamidoamine (PAMAM).2 Incorporating organic component PAMAM has been shown to enhance the corrosion resistance of the conversion coating, as well as to provide binding media for the subsequent paint coating. Despite evidence showing superior performance, the film growth and reaction mechanisms of the hybrid conversion coatings, when incorporating these additives, is not well understood. Here, we studied the effect of the additive PAMAM concentration in the coating solution on the morphology, structure and chemical composition of the coating by a multimodal X-ray and electron analysis. First, we discovered an inverse relationship between the concentration of PAMAM and the thickness of the coating. A higher PAMAM concentration was also found to reduce the Cu-containing cluster formation. Elemental distribution analysis by Scanning Transmission Electron Microscopy with Energy-dispersive X-ray Spectroscopy revealed different microstructure in the surface cluster formation; Cu-containing nanoparticles formed in coatings without PAMAM additives, whereas a more homogenous distribution of Cu species was found in samples with PAMAM. The atomic ratio of elements characterized by X-ray Photoelectron Spectroscopy (XPS) varied with coating conditions. Notably a higher ratio of organic elements indicated the incorporation of PAMAM into the conversion coating with possibly some further adsorption. High-resolution XPS revealed the existence of amide and amine in the coating and different oxidation states of Cu; the results indicate that the reduction reaction of the Cu ions was suppressed by PAMAM, because the complexation between Cu and PAMAM decreased the reduction potential of Cu. In addition, the corrosion of the hybrid coatings in alkaline environment was characterized by synchrotron X-ray Absorption Near Edge Structure (XANES) Spectroscopy showing a better corrosion resistance of hybrid coating with less dissolution of clusters. Overall, the study discussed the interaction between Cu ions and PAMAM and the subsequent effect on the coating morphology and composition as well as the anti-corrosion property. The work furthers the fundamental understanding on how organic and inorganic additives may synergistically act to enhance the properties of the conversion coating. We intend to shed light on the critical processing-structure-property relationship that need be considered and tailored for applying and designing novel conversion coatings for corrosion protection applications. Figure caption: Surface (top row) and cross-sectional morphology (bottom row) of the conversion coatings with 0 to 200 ppm PAMAM concentration in the coating solution. From the surface view, the cluster visually decreases with increase of PAMAM concentration. The flake-like morphology could be observed on sample with higher PAMAM concentration. From the cross-sectional view, the voids and thickness of the coating decreases with increasing PAMAM concentration. Reference: (1) Xiaoyang Liu, D. V., Hua Jiang, Kim Kisslinger, Xiao Tong, Mingyuan Ge, Evgeny Nazaretski, Bruce Ravel, Kate Foster, Stanislas Petrash, Yu-chen Karen Chen-Wiegart. Environmentally Friendly Zr-Based Conversion Nanocoatings for Corrosion Inhibition of Metal Surfaces Evaluated by Multimodal X-ray Analysis. ACS Appl. Nano Mater. 2019, DOI: 10.1021/acsanm.8b02309. (2) Donald Robb Vonk, T. S. S., Alvaro Bobadilla Thin Corrosion Protective Coatings Incorporating Polyamidoamine Polymers. Feb. 8, 2018. Figure 1

In situ monitoring of corrosion processes is important to fundamentally understand the kinetics and evolution of materials in harsh environments. A quasi in situ transmission electron microscopy technique was utilized to study microstructural and chemical evolution of a Ni-20Cr disc sample exposed to molten KCl-MgCl2 salt for 60 s in consecutive 20 s iterations. In situ synchrotron X-ray nanotomography was performed to characterize the morphological evolution of a Ni-20Cr microwire exposed to molten KCl-MgCl2. Both techniques captured key corrosion events and revealed mechanisms at different time and length scales, potentially bringing greater insights and deeper understanding beyond conventional analysis.

The quantitative evaluation of the three-dimensional (3D) morphology of porous composite materials is important for understanding mass transport phenomena, which further impact their functionalities and durability. Reactive porous paint materials are composites in nature and widely used in arts and technological applications. In artistic oil paintings, ambient moisture and water and organic solvents used in conservation treatments are known to trigger multiple physical and chemical degradation processes; however, there is no complete physical model that can quantitatively describe their transport in the paint films. In the present study, model oil paints with lead white (2PbCO3·Pb(OH)2) and zinc white (ZnO) pigments, which are frequently found in artistic oil paintings and are associated with the widespread heavy metal soap deterioration, were studied using synchrotron X-ray nano-tomography and unilateral nuclear magnetic resonance. This study aims to establish a relationship among the paints’ compositions, the 3D morphological properties and degradation. This connection is crucial for establishing reliable models that can predict transport properties of solvents used in conservation treatments and of species involved in deterioration reactions, such as soap formation.

In this paper, we summarize briefly some of the future trends in synchrotron science as seen at the National Synchrotron Light Source II, a new, low emittance source recently commissioned at Brookhaven National Laboratory. We touch upon imaging techniques, the study of dynamics, the increasing use of multimodal approaches, the vital importance of data science, and other enabling technologies. Each are presently undergoing a time of rapid change, driving the field of synchrotron science forward at an ever increasing pace. It is truly an exciting time and one in which Roger Cowley, to whom this journal issue is dedicated, would surely be both invigorated by, and at the heart of.

A versatile, compact heater designed at National Synchrotron Light Source-II forin situX-ray nano-imaging in a full-field transmission X-ray microscope is presented. Heater design for nano-imaging is challenging, combining tight spatial constraints with stringent design requirements for the temperature range and stability. Finite-element modeling and analytical calculations were used to determine the heater design parameters. Performance tests demonstrated reliable and stable performance, including maintaining the exterior casing close to room temperature while the heater is operating at above 1100°C, a homogenous heating zone and small temperature fluctuations. Two scientific experiments are presented to demonstrate the heater capabilities: (i)in situ3D nano-tomography including a study of metal dealloying in a liquid molten salt extreme environment, and (ii) a study of pore formation in icosahedral quasicrystals. The progression of structural changes in both studies were clearly resolved in 3D, showing that the new heater enables powerful capabilities to directly visualize and quantify 3D morphological evolution of materials under real conditions by X-ray nano-imaging at elevated temperature during synthesis, fabrication and operation processes. This heater design concept can be applied to other applications where a precise, compact heater design is required.

Nanoporous metals fabricated by dealloying have a unique bi-continuous, sponge-like porous structure with ultra-high surface area. The unique properties of these materials, especially nanoporous gold, have numerous potential applications in sensors and actuators and in energy-related applications such as catalytic materials, super-capacitors, and battery supports. The degree of porosity and size of the metal ligaments are critical parameters that determine many properties and thus govern the functionalities of nanoporous metals in many applications including energy storage and conversion. We used Fresnel coherent diffractive imaging combined with tomographic reconstruction to quantify the nanoscale three-dimensional spatial distribution and homogeneity of the porosity and ligament size within a bulk sample of nanoporous gold. The average porosity and its standard deviation along the axial direction through the sample were determined, as well as the characteristic feature size and its standard deviation. The result shows that free corrosion is an effective way to create homogeneous nanoporous metals with sample sizes on the order of 1 µm.

Growing interest in molten salts as effective high-temperature heat-transfer fluids for sustainable energy systems drives a critical need to fundamentally understand the interactions between metals and molten salts. This work utilizes the multimodal microscopy methods of synchrotron X-ray nanotomography and electron microscopy to investigate the 3D morphological and chemical evolution of two-model systems, pure nickel metal and Ni-20Cr binary alloy, in a representative molten salt (KCl-MgCl

Synchrotron microscopy visualizes and furthers the understanding of cycling stability of water-in-salt Li-ion batteries., Water-in-salt (WIS) electrolytes provide a promising path toward aqueous battery systems with enlarged operating voltage windows for better safety and environmental sustainability. In this work, a new electrode couple, LiV3O8-LiMn2O4, for aqueous Li-ion batteries is investigated to understand the mechanism by which the WIS electrolyte improves the cycling stability at an extended voltage window. Operando synchrotron transmission x-ray microscopy on the LiMn2O4 cathode reveals that the WIS electrolyte suppresses the mechanical damage to the electrode network and dissolution of the electrode particles, in addition to delaying the water decomposition process. Because the viscosity of WIS is notably higher, the reaction heterogeneity of the electrodes is quantified with x-ray absorption spectroscopic imaging, visualizing the kinetic limitations of the WIS electrolyte. This work furthers the mechanistic understanding of electrode–WIS electrolyte interactions and paves the way to explore the strategy to mitigate their possible kinetic limitations in three-dimensional architectures.

Metal (M) oxides are one of the most interesting and widely used solids, and many of their properties can be directly correlated to the local structural ordering within basic building units (BBUs). One particular example is the high-Ni transition metal layered oxides, potential cathode materials for Li-ion batteries whose electrochemical activity is largely determined by the cationic ordering in octahedra (e.g., the BBUs in such systems). Yet to be firmly established is how the BBUs are inherited from precursors and subsequently evolve into the desired ordering during synthesis. Herein, a multimodal in situ X-ray characterization approach is employed to investigate the synthesis process in preparing LiNi0.77Mn0.13Co0.10O2 from its hydroxide counterpart, at scales varying from the long-range to local individual octahedral units. Real-time observation corroborated by first-principles calculations reveals a topotactic transformation throughout the entire process, during which the layered framework is retaine...